SOFT-SEDIMENT MEIOFAUNAL COMMUNITY STRUCTURE IN RELATION TO A LONG-TERM HEAVY-METAL GRADIENT IN THE FAL ESTUARY SYSTEM

The Fal estuary system, southwest England, is an ideal site for a natu ral experiment on the effects of long-term contamination by heavy meta ls on intertidal mudflat meiofauna communities. Five creeks were chose n in which sediment concentrations of heavy metals differed by orders of magnitude, namely Restronguet (mean Cu concentration 2532 mug g-1), Mylor (1272 mug g-1), Pill (697 mug g-1), St Just in Roseland (332 mu g g-1) and Percuil (165 mug g-1). Univariate and multivariate analyses of the meiofaunal community structure in these creeks suggest that ne matodes are more responsive to sediment heavy metal concentrations tha n copepods, as indices of diversity and changes in nematode community structure as revealed by multivariate analyses were closely correlated with metal levels. For copepods differences could only be detected in Restronguet creek, where endobenthic species were absent. Analyses su ggest that some nematode species may have developed different toleranc e mechanisms for survival in areas with high heavy metal concentration s.